A PARAMETRIC STUDY OF PART DISTORTIONS IN FDM USING 3D FEA

摘要

We developed a finite element model to simulate the fused deposition modeling (FDM) process. The model considers the coupled thermal and mechanical analysis and incorporates the element activation function to mimic the additive nature of FDM. Due to repetitive heating and cooling in the FDM process, residual stresses accumulate inside the part during the deposition. The model is also used to evaluate the part distortions, revealing distortion features such as vaulting shapes and distortion-core shifting. A parametric study, three factors and three levels, was performed to evaluate the effects of the deposition parameters on residual stresses and part distortions. Prototype models with larger sizes were fabricated, measured, and compared with the simulations. The simulation results show that (1) the scan speed is the most significant factor to part distortions, followed by the layer thickness, (2) the road width alone is insignificant, however, the interaction between the road width and the layer thickness is significant too, and (3) there are other two-way and three-way interactions that are of secondary significance. Residual stresses increase with the layer thickness, and increase with the road width, to a less extent though, yet largely affected by the layer thickness. The FDM part distortions from the experiment show a similar trend as in the simulations, but no quantitative correlation.